Spark plug shield



Sept. 12, 1950 A. H. CADMAN SPARK PLUG SHIELD Filed June 12, 1946- Patented Sept. 12, 1950 UNITED STATES PATENT OFFICE.

SPARK PLUG SHIELD Arthur H. Cadman, Bloomfield, N. J., milnfll' to Breeze Corporations. Inc., Newark, N. J a corporation of New Jersey Application June 12, 1946, Serial No. 676,311

1 Claim. (01. 174-35) This invention relates to shields such as are placed around spark plugs of internal combustion engines, and particularly such as are adapted to prevent the ignition system from interfering with radio communication.

An object of this invention is to provide a spark plug shield which may be applied to any standard spark plug.

Another object of this invention is to provide an easily assembled spark plug shield.

A feature of this invention is the locking cap member which permits of easy inspection and installation.

Another feature of this invention is the metal foil liner which insures the metal-to-metal contact between the shield shell and the cap.

An object of this invention is to provide a shield to be used on motors where the spark plug is held within a recess in the engine block.

A further object of this invention is to provide an extremely light and inexpensive radio shield for a spark plug.

The invention consists of the construction, combination and arrangement of parts, as hereinafter illustrated, described and claimed.

In the accompanying drawings, forming part hereof, is illustrated one form of embodiment of the invention, in which drawings similar reference characters designate corresponding parts, and in which:

Figure 1 is a side elevation of a complete embodiment of the invention, with the cap member cut away to show the construction thereof and certain hidden portions shown by dotted lines.

Figure 2 is a longitudinal section of the cap member.

Figure 3 is a bottom plan of the cap member, partly broken away.

Referring to the drawings, and particularly to Figure 1, i0 represents a metallic shell somewhat cup-like in shape. The lower portion of the shell is flared inwardly at H to meet the base 52 thereof. A hole i3 is provided in said base 82 for the admission therethrough of the lower portion of a spark plug it. A reinforced rim member I! is secured to the upper edge of the shell i8 by silver solder at ii. The rim member i5 is provided with a rim bead H for the purpose of receiving a cap member i8 and holding said cap'memher to the shell to.

The cap member it, as best shown in Figure 2, is provided, along its rim, with a plurality of peripheral detents I. The detents I! have their extending ends 2! turned back upon themselves toreceivealockingwirefl. Thewirefl ispassed through said detents i9 and is engaged by a looking lever 22 formed of another piece of wire.

The operation of the locking device is well known. When the wire 22 is pressed downwardly.

the locking wire 2| is drawn more tightly around the cap member ll, thereby securing it to the rim member iii. A gasket 24 is inserted in the upper portion of the cap member II and may be of rubber or any similar insulating material. A layer of metal foil 23 is disposed upon the upper surface of the gasket 24 in such manner that the extending edges 25 of said foil 23 may be brought over the periphery of the gasket 24 so as to lie upon the lower face of said gasket in a circular ring. as shown in Figure 3.

When the cap member II is applied to the reinforced rim I! of the spark plug shield, and the locking leve 22 pressed downward, the foil edge 25 of the foil liner 23 provides a metal-tometal contact between the shield shell l0 and the cap member I8.

The shell member ll is provided with an opening 20 spaced from the upper edge of the shell II, for the purpose of admitting the contact 21 of the ignition cable 28. An externally threaded outlet shield 29 is carried by the shell body ll. adjacent this opening 26.

In applying this shield to the motor, the spark plug 14 is first removed from the engine block and then inserted in the opening l3 in the spark plug shield shell to. The spark plug I0 is then threaded back into the engine block until the base l2 of the spark plug shield is tightly held between the hexagonal member 30 on the spark plug and the block surface. This assembly grounds the shield to the engine block. The ignition wire contact 21 on the cable 28 is then pulled through the outlet 29 into the shell chamber and contact made between the spark plug it and the ignition cable.

The coupling nut 3i located on the ignition shielding conduit 32 is tightened on the external threads of the outlet shield 29. When the electrical connection is made, the cap member i8 may be pressed downward over the reinforced rim member is of the shell l0 and the locking wire 2! drawn tight by forcing the locking lever 22 downwardly. v

The edges 25 of the foil liner 23, best shown in Figure 3, complete the electrical contact of the spark plug shield. Breather holes 33 are pro= vided in the inwardly flared portion of the shell II, and also along the central portion of the rim section l5. These holes 33 prevent the collection of moisture within the spark plug shield.

, 3 4 The simplicity or the operation and construction of this spark plug shield become apparent from the foregoing description.

It is adaptable for all types of engines, and the inwardly flared portion of the shell body makes it possible to use this shield on eniinee where the spark plug is retained in 'a well or recess in the cylinder block. 7

Having thus fully described theinvention, what is claimed as new and desired to be secured by Letters Patent of the United States, is:

In a, spark plug shield, an electrically conductive shell comprising a cylindrical member inwardly flared at its base and provided with an intumed flange at the bottom thereof adapted to fit snugly around the base of a, spark plug, a wire spring retained cap member secured thereon comprising a plurality of detents integral with said cap' and having their ends turned back upon themselves to receive the said wire and a lever adapted to draw the said cletents together by means of the wire, said cap supporting, upon the inside surface thereof, a resilient gasket having asaaoro a layer of metal foil disposed upon the upper surface thereof and continued over the edges of the said gasket to form a peripheral strip upon the lower surface thereof and a shielding outlet carried by the wall of the said shell to admit an ignition cable into the shield.

' ARTHUR H. CADMAN.

REFERENCES CITED.

The following references are of record in the file ot this patent:

UNITED STATES PATENTS 

